last refactoring of terrain feature (#3702)

* last terrainFeature refactorings

* cut down terrainFeature as much as possible

* aerialDistanceTo fixed

wrapped distance should only be considered on wrapped worlds

* Adding spaces

* fixed tests not compiling

* prevent floodplains from spawning on oasis

* Check if terrain feature can be placed on tile in editor

* Adding reviewed changes

tests/src/com/unciv/logic/map/UnitMovementAlgorithmsTests.kt

@@ -97,7 +97,8 @@ class UnitMovementAlgorithmsTests {
     @Test
     fun canNOTEnterIce() {
         tile.baseTerrain = Constants.ocean
-        tile.terrainFeature = Constants.ice
+        tile.terrainFeatures.clear()
+        tile.terrainFeatures.add(Constants.ice)
         tile.setTransients()
 
         for (type in UnitType.values()) {